Telephone system



k TELEPHONE SYSTEMv Filed July 5. 1934 2 Sheets-Sheet l sa o :Q1 LD l m d co O L) c() y l pr u n c fp, C LJ ELE- wmb 1+ A d +1 j L N INVENTOR THOMAS E CROCKER ATTY.

April M, E936. T. F. cRocKER 2,037,234

' TELEPHONE SYSTEM Filed July 5, 1954 2 Sheets-Sheet 2 INVENTOR THOMAS FCROCKER Patented Apr. 14, 1936 UNITED STATES PATENT [oFFlcE 2,037,214 Y TELEPHONE SYSTEM Thomas F. Crocker, Chicago, Ill., assignor to ssciated Electric Laboratories, Inc., Chicago,

Ill., a corporation of Delaware Application `Iuly 5, 1934. Serial No..733,762 130mm. (o1. 179-51) The present invention relates in general to telephone systems, but is particularly concerned with the provision of improved night alarm, line terminating, busy test, and cord circuits of a manual telephone system.

In the customary night alarm circuits heretofore employed the line lamps have been actuated in a circuit including an alarm control relay. It has always been a problem to keep this relay in proper adjustment, owing to Ythe fact that in wet weather the accumulated line leakage through the line lamps often becomes Sullicient to operatethe relay. When the relay is more stiflly adjusted it operates satisfactorily until the line leakage again decreases to a point where the current o'w increase effected by the initiation of a call is insumcient to operate it. It then becomes necessary to readjust the relay to meet the new condition. I

One feature of the invention has to do with the provision .of a night alarm circuit wherein a gra-dual variation in line leakage cannot affect the proper operation of the alarm relay, and wherein cross-talk Ybetween calling subscribers ,waiting for the operator is positively prevented.

Another feature has to do with the provision of an improved convertible line equipment, i. e., equipment which may be originally employed for serving a local battery line and may later be readily converted to serve a common battery line.

The line terminating equipment for common battery lines of a multiple type switchboard, when busy, are so characterized by the presence of ground potentialv von the sleeves of .their multiple line jacks,'whereas in the line terminating equipmentof local battery lines battery potential is placed on the sleeves of the jacks of such lines.

A still further feature of the present invention has to do with the provision of Vmeans whereby the operator receives the same indicationlirespective of the type of line beingtested.

Other features have to do with the provision of a .very simple form of cord circuit.

The invention is illustrated in two sheets of drawings comprising Figs. 1 and 2, respectively, which, when Fig.v 1 is placed immediately over Fig. 2, diagrammatically show suicient' circuits Y and apparatus to enable the following description of the various feature of the invention toy be readily understood.

In Fig. 1 is shown a cordcircuit C with an associated operators telephone circuit OTC. This ",figur'e also shows non-multiple and multipled line terminating equipment for local and common battery, lines.

Fig. 2 also shows other non-multiple and multiple line terminating equipment for local and common battery lines. This gure also shows, within' the dashedline rectangle, the novel night alarm equipment employed.

When a call is initiated at a local battery telephone, having its line terminating in local battery line equipment LBI the current generated by the magneto of telephone TI passes through contacts 2, the lower winding of relay l, the vContact and ring element of jackfJ l, over theotherside of the subscribers line. The con'- tacts 3 of'rela'y I make before contacts 2 break and complete a locking circuit for relay l This circuit extends from the grounded side'of thev exchange battery, through the upper winding of relay l, the Lamp Ll, conductor and through lower contacts vof the night alarm'key NK to the ungrounded side of the exchange battery.v If the key NK is in operated position the operating path includes the primary windings of the repeating coil RC.

The answering and calling ends of the cord C are symmetrical except thatv provision for ringin'g out over the calling end only of thecord is provided; To answer the call the operator inserts the plug PI of cord C into the jack J I. The operating vand holding paths through the Winding of relay I are thereby interrupted and the relay restores. The lam'p LI is accordingly extinguished and the upper conductor of the line Ais again connected to the tip side of the jack. The operator'Y may now actuate the combined listening vand ringing key K to listening position and conversewith the calling subscriber.

' If the calling subscriber desires a connection with. another local battery telephone, the telephone Tl, for example, the operator inserts the plug P of the cord in jack J1. This effects the removal of the winding of the line drop D3 from in bridge of the associated line and the connection of thetip and ring conductors of the cord thereto. The operator vmay now roperate her key K to ringing position to manually signal the called station.

None of the relays of the cord circuit are actuated in the connection described. Since this is the `case, the supervisory drop SD in the cord circuit remain'sin bridge of the ring and tip conductorsthereoi and, maybe operated by currentY generated by the magneto of either of the connected stations to signal the operator.

The' line terminating equipment LB4 is like that of LB3 except that it is there shown as employed in a multiple type switchboard. Full metallic lines such as employed to connect station T'I with LB3; ground return lines such as L4, or ground return lines such as L5, equipped with a repeating coil when it is necessary to insulate a line on account of excessive noise, may be connected to line terminating equipment such as LB3 or LB4.

When a line is connected with over a local battery line multiple jack, such as J4, the sleeve terminals of the multiples thereof will be marked as busy by the connection of the ungrounded pole of the exchange battery thereto via either resistance 23 or 24.

If the calling subscriber at station TI desires connection with station T2 in lieu of T'I the operator inserts the plug P into the jack J2 of this local battery line. This effects the disconnection of the lower winding of relay 4 from in. bridge of the line and connects the tip and ring conductors of the line with the corresponding conductors of the cord. As in the prior example the sleeve of plug P connects the ungrounded pole of the exchange battery to the sleeve terminal of jack J2 and its multiples to mark the line busy. Line equipment LB2 is otherwise like LBI.

If the subscriber at station TI desires a connection with a common battery station, the station T3, for example, the operator inserts plug P into jack J3, thereby connecting the line conductors of T3 with the tip and ring conductors of the cord and disconnecting the call signal L3 and battery from in bridge of the line. The direct ground potential on the sleeve of jack J3 effects the operation of the front sleeve relay I6. This ground completes circuits through the lower winding of this relay to battery and through the upper winding of this relay, the back contact and armature I4, and through the supervisory call lamp L9 to battery. The relay I6 accordingly operates, at armatures I'I and I8 and their front contacts connects the battery feed relay I3 in bridge of the tip and ring conductors of the calling end of the cord, now connected with the line conductors of station T3;

and at its armature I9 removes the supervisoryy drop from in bridge of the ring and tip conductors of the cord and connects the lower Winding of the back sleeve relay I in bridge of the tip and ring conductors on the answering side of the cord.

The operator manually transmits signalling current out over the called line by holding key K in ringing position. Upon the response of the called party the relay I3 becomes energized over the called subscribers loop and at armature I4 interrupts the circuit traced through the call supervisory lamp L9 and the upper winding of relay I6. The lamp 9 is accordingly extinguished to advise the operator of the response of the called subscriber.

When the conversation has been completed and the called subscriber replaces his receiver relay I3 again restores and thereby reestablishes the circuit through lamp L9 which serves to give the operator disconnect supervision. If the local battery subscriber desires to signal the operator he may also do so by operating his magneto. The current generated will flow through armature I9 and its front contact, contacts I2, back contact and armature 8, and the lower winding of relay I0 to the other side of the line. Relay accordingly operates, and at armature II and its Working contact closes a locking circuit for itself before contacts I2 open. This circuit extends from ground through the upper Winding of relay I0, armature 1 and its back contact, the upper break listening contacts of the key K, the front contact and armature II, and lamp LIU to the ungrounded pole of the exchange battery. The lamp LIB lights over this circuit.

Withdrawal of the plugs P and P from the jacks J3 and J I brings about the restoration or' the circuits to normal.

'Ihe line equipment CB4 is like that of CB3, merely showing the application to a multiple type board. Obviously, when a plug is inserted in one of the jacks of equipment CB4 the sleeve terminals of the associated jacks are grounded to identify the line as being in use.

The operations which ensue following the establishment of a connection from any local battery station to any other common battery station of the types shown are the same as those just described. Y

Calls incoming over local battery lines having line terminating equipment such as LB3 are handled by the operator in a similar manner to those incoming over equipment such as LBI, except that the conventional drop D3 is employed as a call signal.

When a call is initiated from a common battery station, station T3 for example, the operator inserts plug PI into jack J3 thereby effecting the disconnection of the lamp L3 from in bridge of the line and the operation of the answering sleeve relay 5. Since, as previously stated, both halves of the cord C are symmetrical, it will be obvious that the relay 5 will operate over circuits identical to those traced through relay I6. It will further be seen that, since the calling loop is already closed, the answering sleeve relay I0 will operate and prevent the lighting of answering supervisory lamp LIU at this time.

To complete a connection to a local battery line it Will be obvious that the operator inserts the plug P into the jack of such line and operates the key K to ringing position.

When conversation has been completed and the calling subscriber replaces his receiver the battery feed relay restores and establishes the circuit through the. lamp LIU. The local battery subscriber can also effect the operation of lamp L9 in the same manner that LI 0 was operated when the call originated at a local battery station.

If a connection with another common battery station is desired, station T5 for example, the operator inserts plug P into jack J5, thereby connecting the tip and ring conductors of the answering end of her cord to the line conductors of station T5 and disconnecting the relay 3I and battery from in bridge thereof. The ensuing operations are the same as those which occur in the establishment of a connection to station T3. Upon completion of the conversation the replacing of the receivers at the respective stations causes lamps L9 and LIU to light up and give the operator disconnect supervision.

Particular attention is now directed to the line terminating equipment CBI, which is like that of LBI except that the circuits have been slightly changed to convert a former local battery line equipment such as LBI into common battery line equipment. This has been accomplished by placing a shunt 32 about the break contacts of this relay and by connecting both windings and the exchange battery normally in bridge of the line.

Shemale key is later restored; and at l'ccntactsfcorn When a call is initiated overtheline terminating in equipment CBI the `relay A3| operates over `'the closed line loop to effectv the lighting of its line lamp, and is disconnected from the line "bythe insertion of a plug in the associated jack J5.

Subsequent Aoperationsin the establishment of connections between a line terminatingin-equipment'such as'CBI and other lines will bereadily understood. f

When a multiple type switchboard i'semployed the operator tests the desired'line for a busy con' dition by Vtouching the tip yof her calling plug P against the sleeve terminal of thejack of such line locatedat herposition. It will be assumed, forexample, that'localbattery station LB2 is the on'e'withwhich a connection is desired, andthat the line has been taken for use by an operator at the position at which J 2' appears. yThe touching of/plug P against the sleeve of jack J2 com-'- pletes a circuit from the grounded terminals of the exchange battery, through resistance 26, contacts of the operators battery feed relay 21, the tertiary winding of the induction coil, operated listening contacts of key K, the break contacts controlled by armature I8 of sleeve relay I6, the upper break ringing contacts of key K, the tipy of plug P, the sleeve of jack J2, and the'sleeve of jack J2 to battery via a resistance such as 23 or 24 of a cord like Cemployed in the prior connection Vwith the desired line. The click produced in the receiver of the operators telephone circuit upon completion of the traced circuit advises her of the existing busy conditionfof the desired line.

If a connection with a common battery line is desired the operator makes a like busy test. Since, however, these lines are identified as busy'by placing ground potential on the sleeves of their jacks thev test circuit includes, at the operators telephone circuit, resistance-25 and the ungroun'ded pole of the exchange battery. It will be obvious that when the operators telephone circuit OTC is to be employed with a non-multiple type board, the testing portion of the circuit may be omitted.

When the night ralarm key NK is in operated position the connection of the ungrounded pole of the exchange battery directly with the common current supply lead 50 for all linelamp signals of the board is interrupted by the break contacts of this key and accordingly the normal shunt about the primary windings of repeating coil RC is removed.

The` key NK also1at its upper make contacts closes a point in an' operatingfcircuit of alarm relay'33, at its middle make contacts closes an obvious circuit including the polarizing winding of relay 31, and at its lower make contacts includes the operating winding of this relay in series withfthe secondary winding Voi the repeating coil RC. Under these vcircumstances when a call is initiated over any line terminatingin line equip-v ment employing a lamp-type call signal, the current for operating such signal passes through the primary windings of RC, thereby inducing a momentary surge of current in itsgsecondary winding. This surge of current effects the operation of relay 31. 'I'he polarizing winding of this relay is then sufficient to'hold the same operated. The relay 31 upon operating completesan obvious circuit for the alarm relay 33. This relayaccordingly operates andat its contacts 34 closes the circuit of the night alarm A. `'I'he relay 33 also',

, at contacts 35, opens -thfe Aoperating circuit of .re-

lay 31 to prevent its possible reoperation when nec't'sfthe ungroundedpolecf the exchange bat# tery-toconductor thereby again placing a shunt about'theprimary-windingof the repeating coil RC to preventeother subscribers waiting Aloi* vthe operator, from-being-able to talk to eachother through the induc'tance-other'wise aio'rde'd by the primarywindings of RC.

To- Arestorethe night alarm circuit to-norm'al after it has Yonce benopcratedrby the surge of currentas-described, the operator must v'restore key NK. Upon restoration of this' key-thecircuit through the polarizing winding of relay 31 is interruptedfcausing'lthis relay to restorei Themiddle niakecontacts of-key NK are adjusted-tobreak first morder-'to positively prevent arfalse '.kick upof relai7 31 which otherwise-might rresult if contacts 35 are closed before the middlecontacts of NK areopened.

When all of the existing' callshave been dis= posed of the operator may again prepare :the night alarm circuit by reoperating the key NK.

It will be quite obvious that the'initiation of calls over local battery lines equipped .withl line drops, directly effects the completion of .a circuit through the alarm relay 33 kin Athe customary manner. Under these circumstances it will be obvious that the alarm relay restoreswhen all actuated line drops have been restored.

Having described the invention,what is con-'-y sideiedto befnew and is desired to-'be protected by Letters Patent will be set forth in the following claims.

What isv claimed is:

1. In a telephone subscribers line terminating equipment a relay having two windings, a .jack having pairs of normally closed contacts,` aline signal, an operating circuit for said relay including one of its windings and one pair of the normally closed contacts of said-jack in series` with the other winding of said relay and anotherpair of contacts Iof said jack, and a circuit for said signal controlled by said relay.

`2. In a telephone system, a subscribers line,- a line-jack in which the conductors of said line terminate, a two-winding line relay, contacts in said jack through the medium ofwhich one. ter` minal of eachof'the windings of said relay are connected to the conductors of said line, a source of current connected to the otherterr'ninals of the windings ofsaid relay, subscriber actuated means for completing a circuit over said line through saidcontacts and through both windings of said relay to operate the same, and a rline- `signalv controlledby said relay. l

3.' In a telephonesubscribers line terminating equipment, a relay havingtwo windings, a call signal, a jack, an operating circuit for said relay including contactsv of said relay, one of its windings, and contacts of said jack, and a locking cir-4 cuit for said relay including said call signal in series with other contacts of said relay, other contacts of said jack and its other winding.

4. In a telephone system, a calling line, line' equipment at a central exchange in which said line terminates, a line signal associated with said equipment, an operating circuit for said signal closed by said equipment in response to the initiation of a call over said line, a signal auxiliary to said line signal, arelay for controlling the operation `of said auxiliary signal, and means included inthe operating circuit of said line signal circuit for inducinga current ilow in said relay s'uiflcient to operate it.

5.l In a telephone system,- a calling line, line' line terminates, a line signal associated with said equipment, an operating circuit for said signal closed by said equipment in response to the initiation of a call over said line, a signal auxiliary to said line signal, a relay for controlling the operation of said auxiliary signal, means included in the operating circuit of said line signal `circuit for momentarily inducing a sufficient current flow through said relay to operate it, and means for thereafter maintaining said relay operated until the call is answered. A

6. In a telephone system, calling lines, a night alarm signal, circuit arrangements for controlling said signal including an electro-polarized relay; a repeating coil having its secondary winding included in circuit with the operating winding of said relay, line signals of said system supplied with operating current through the primary winding of said induction coil when any of said lines initiates a call, the induced current iiow in the secondary resulting from the initial current flow in the primary whenI any line of the system initiates a call, being sufcient to effect the actuation of said relay, a second relay having an `operating circuit closed by said first relay, contacts on said second relay for interrupting the operating circuit of said first relay, other contacts on said second relay effective to actuate said night alarm signal; and further contacts on said second relay for short circuiting the primary winding of said repeating coil to Vprevent subscribers on other calling lines, waiting for the operator, from talk-A ing to each other through the inductance afforded by the primary winding.

7. In a telephone system, calling lines, a night alarm signal, circuit arrangements for controlling said signal including an electro-polarized relay; a repeating coil having its secondary winding included in circuit with'the operating wind` ing of said relay, line signals'of said system supplied with operating current through the primary winding of said induction coil when any of saidlines initiates a call, the induced current ow in the secondary resulting from the initial current flow in the primary when any line of the system initiates a call, being sufiicient to effect the actuation of said relay, a second relay having an operating circuit closed by said first relay, and means controlled by said second relay for actuating said 'night alarm signal and for preventing calling subscribers from talking to each other through the inductance afforded by the primary windingof said repeating coil.

8. In a line equipment for a subscribers line of a manual telephone system, a double Wound relay having an operating circuit including a source of current and its two windings in series with the conductors of a subscribers line when such line is equipped with a common battery type of telephone; including break contacts of the relay and one of its windings in seriesrwith the conductors of a subscribers line when such line is equipped with a magneto type of telephone; and a locking circuit for said relay, when employed with a line equipped with a telephone of the latter type, including a pair of contacts thereof, the line sign-a1 of such line and a source of current.

9. In a telephone system, calling lines, line signals individual to the respective calling lines, a common operating circuit path for said signals with individual branches, means controlled over said lines upon initiation of calls thereover to close their respective signal circuits, a relay havequipment at a central exchange in which said ing its operating winding inductively connected to said common operating current path and operated by an induced current resulting from any calling line initiating a call, means for thereafter maintaining said relay operated independently of said inductive connection, and means controlled by said relay for actuating a signal to notify an operator that at least one of said lines has initiated a call, and for also'disabling the inductive relationship between said common circuit path and said relay, thereby preventing subscribers of other calling lines from communicating withreach other through this-otherwise inductive circuit..

10. In a telephone system, local and common battery subscribers lines terminating in multiple line jacks at a central exchange, a universal cord circuit for establishing connections between said lines, means for placing battery potential of one polarity on the sleeves of the jacks of certain of said lines to mark them as busy, means for placing potenti-al of the opposite polarity on the sleeve of the jacks of other lines to mark them as busy, and means in said cord circuit responsive to in like manner advise an operator of such busy condition when the tip of a plug of said cord is touched against the sleeve of the jack of a busy line.

11. In a night alarm circuit for a central exchange, a night alarm signal control relay actuated directly over a circuit including contacts closed by the actuation of a line drop of a magneto line responsive to the initiation of a call over a magneto line; a second relay, for controlling said signal through the medium of said first relay, having a normally energized polarizing winding, and having an operating winding inductively connected in a common operating circuit provided for the line signals of calling lines of the common battery type and operated by current induced in its operating Winding responsive to the initiation of a call over a common battery line, and means controlled by the actuation of said first relay for disabling the inductive relationship between said second relay and said common operating path to prevent cross-talk. Y

12. In a telephone system, a plurality of local and common battery lines terminating in suitable jacks of a telephone switchboard, a cord circuit for establishing connections between said lines, a supervisory signal in said cord normally in bridge of the tip and ring conductors thereof and operaable by current generated by either of a pair of connected local battery lines, a pair of lamp signals in said cord, a relay in said cord operated in response to the connection of a local battery line with a common batteryv line for removing said supervisory signal from in bridge of the tip and ring conductors of said cord, means placed in bridge of theanswering end of said cord by said relayv controllable by a subscriber of the local battery line for actuating one of said lamp signals, and a relay having means for controlling the other of said lamps placed under the control of' a subscriber of the common battery line by the operation of said first relay.

13. In a telephone system, a cord circuit for use in interconnecting local and common battery lines, a supervisory signal normally in bridge of the tip and ring conductors of said cord for use solely by either of the subscribers of a connected pair of local battery lines to signal the operator, a pair of lamp signals in said cord, sleeve and battery feed relays, respectively, in each end of said cord, a circuit for the sleeve relay of one end of the cord completed by the connection of such` end of the cord with a common battery line, means actuated by such relay to connect the associated battery feed relay and a source of current in bridge of the common battery line connected with, other means actuated by said relay to remove said supervisory signal from in bridge of the cord and for connecting a Winding of the other battery feed relay in bridge of the far end of the cord, local battery station controlled means for actuating the latter relay, a locking Acircuit for the latter relay including one of said lamps, such lamp operating over said locking circuit to signal the operator.

Y THOMAS F. CROCKER. 

